A simple method of preparing graphene-coated Li[Li0.2Mn0.13Co0.13]O2 for lithium-ion batteries

Graphene-coated Li[Li0.2Mn0.13Co0.13]O-2 is synthesized by the spray drying method. The morphology and electrochemical performances of the pristine and graphene-coated cathodes have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), charge-discharge measurements, as well as Ac impedance spectroscopy. At 250 mA g(-1), the pristine and graphene-coated samples deliver capacities of similar to 141 and 153 mAh g(-1) with capacity retention of 80 and 97% in 50 cycles, respectively. An analysis of the charge-discharge capacity values and electrochemical impedance spectroscopy (EIS) measurements reveal that the improved electrochemical performances of the graphene-coated sample are due to the suppression of the solid-electrolyte interfacial (SEI) layer and the enhancement of surface electronic conductivity. (C) 2012 Elsevier B.V. All rights reserved.